Login script would require users to have admin rights to uninstall.

Not sure what version of WinZIP added the silent uninstall switch of:
WINZIP32.EXE /uninstallx

If 7.0 has it you would add:
 Code:
If Exist($PathToFile + '\WINZIP32.EXE')
  Run $PathToFile + '\WINZIP32.EXE /uninstallx'
EndIf
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Give a man a fish and he will be back for more. Slap him with a fish and he will go away forever.